Here are some basic impressions I have discovered and all these are my own opinions.
Bowser Jr {A+}
-Great ground game
-OverB is a strong gap closer and being able to hop cancel into any air attacks is a wonderful mix-up
-NeutralB is great for zoning and edge guarding, bad for using in the middle of the stage as a normal attack
-Very mobile
-Good KO attacks
-Excellent recovery both vertically and horizontally
-Tilts forward, down and up are very strong for damage, range and knock back
-DownB (toy) is a great spacing tool for Bowser Jr to get back into the fight and disrupt characters
-Highly aggressive or campy technique is effective
---Rumored to reduce damage if the flying cup is hit and take normal damage if Bowser Jr's body is hit
/
Robin {A}
-Deals a lot of damage with special sword and magical attacks
-SideB is a fantastic spacing tool as well as combo starter/disengage tool
-UpB is good for disruption and recovery
-Aerial attacks with special sword are nasty!
-Takes a lot of time to learn sword and book cool downs
-Even without unique attacks, very strong
-DownB is amazing for damage dealt vs damage recovered (has 45 second reset though...)
-Limited options without magic spellbook
-Pacing is KEY to winning, spamming attacks uses up your limited powerful abilities
Little Mac {not sure B-A maybe}
-Has the BEST ground game of all characters
-Dash attack deals a lot of damage and knock back
-NeutralA has almost no lag out of dash and racks up massive damage
-OverB is great for disengage, mix-ups and mind games
-DownB (counter) is bad, but can get you out of aerial mix-ups
-Cannot handle being in the air for any reason
-Aerials are AWFUL
-With proper spacing and timing can decimate opponents, just rushing in and attacking will not help you win
-Requires a LOT of spacing and proper timing to be good
-Mix up with grabs and tilts to be most effective
Greninja {A+}
-Has amazing ground game and air game
-Smash attacks have great range and are deceptive with hit boxes
-Tilts are good range and damage
-NeutralB (shuriken) has great long range stun and medium range damage (when fully charged) Very important part of kit for spacing and stuns
-Dair bounces off shields
-Uair deals a lot of damage and KO's at good levels
-OverB (shadow sneak) is very important not to spam. Cool down leaves you open to too much punishment. Use sparingly
-NeutralA is great for racking up quick damage
-Can stick to walls
-Great recovery
-Takes skill to rack up damage and KO. Not a straight forward character. Requires creativity to achieve KO's
Olimar {meh, C-}
-Only 3 Pikmin on stage now
-Pikmin follow set pattern now
-Damage from Pikmin is the same as Brawl in element type and damage/knockback
-UpB recovery is greatly improved, can attack out of it
-Feels slower somehow
-Attacks have long recovery times (OverA Smash, DownA Smash)
-Pikmin die just as fast as Brawl
-Olimar can no longer throw 2-3 Pikmin and still have Pikmin ready to smash attack with like in Brawl, you are limited to throwing 1-2 and then having 1 left to defend with
-Olimar has trouble being aggressive or campy with only 3 Pikmin available
Luigi {B}
-Great aerials
-Fair is now godly, can use 3-4 times with a normal jump
-OverB (Luigi rocket) feels weaker now
-Ground game is good
-Luigi excels in the air with grreat damage and priority
-Decent recovery
-NeutralB (fireball) is great for spacing
-Very average, nothing great or awful to speak of
-FUN TO PLAY
/
Wii Fit Trainer (WFT) {C}
-Biggest disappointment in SSB4
-Very basic character, nothing amazing
-Attacks have mediocre range
-Seems to have better knock back than most characters
-Poor recovery
-OverB (soccer ball) used as spacing tool, can change angles depending on how long you hold B button
-DownB is very hard to get correctly. Healing is minimal but damage boost is very good
-Tilts are best attacks for WFT (Ftilt and Utilt)
-Hard to KO with
-Needs to spam NeutralB with tilts to rack up damage
Roselina and Luma {A+}
-Amazing spacing and toolkit
-Hard to grab because you can still control Luma while grabbed
-Basic attacks are very good
-Smashes deal considerable damage and knockback
-Luma has meduim-low HP and can be KO'd quickly
-Great recovery
-DownB helps her stay competitive in the projectile game
-Requires a lot of skill and foresight to be effective
-Very campy character
-Requires good timing on Luma throw and attacks
-Does not engage directly unless absolutely necessary
-Solid aerials, not amazing, not bad. Basic, fundamental aerials
- GREAT in 2v2 games
Shulk {I have no idea}
-Feels like Ike 2.0
-LONG range Fsmash
-Pretty good counter (downB)
-NeutralB (mondo arte) is very hard to use properly, when used right Shulk is a beast
-Requires a lot of practice to use properly
-Everything about Shulk CAN be great when proper mondo arte is used. Or everything can suck when used wrong
-Fair and Nair are very good for range, spacing and damage
-Jump (green arte) gives AMAZING recovery